OCR Chemistry F321 22nd June 2015 *OFFICIAL THREAD*

Could someone please explain the reactivity trend down group 7 and group 2???

Could someone please explain the reactivity trend down group 7 and group 2???

Group 2:
To react, a group 2 element has to lose electrons

Reactivity increases down the column as the atom size increases due to increasing number of shells which therefore means that it's easier for an atom to lose an electron and react TL;DR electrons further from the nucleus, easier to lose

Group 7:
To react, a group 7 element has to attract electrons

Reactivity decreases down the column as the outer shell is further away from the nucleus. It is harder for the nucleus to attract an electron because of the increasing distance. TL;DR electrons further away from the nucleus, harder to attract

Group 2
-reactivity increases as you go down
-as you go down, number of shells increases
-therefore atomic radius and electron shielding increases
-therefore weaker force of nuclear attraction on the outer electron
-means that outer electron is easier to lose, and group 2 elements react via losing outer electrons

Group 7
-reactivity decreases as you go down
-same factors as group 2 metals
-group 7 halogens react by gaining electrons, but as there is more shielding and less nuclear attraction on the outer electrons the further you go down, electrons are harder to gain, so are less reactive

Basically the same explanation, but they react in different ways, leading to different reactivity trends. Also, as a sidenote, the number of protons in the nucleus does increase as you go down the group, but this has little effect compared to electron shielding and atomic radius effect.

Hope this helped

Hey guys i thought I would make a thread for those taking the F321 exam this Friday! Any tips? Also does anyone have predictions for the 5/6 mark questions at the end?

Good luck!

Thanks so muchh xx Very helpful !!

any key topics anyone thinks is likely to come up and worth revising?

I've done 2 past papers for chemistry in the past 24 hours and achieved 60/60 marks for both of them. I marked the first one by myself and my chemistry teacher marked my second one (as well as checking over the first one I marked myself).

Feeling really confident for the chemistry exas this year.

Also, does anyone have last years f321 paper? Are we allowed access to it yet?


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